1. Field of the Invention
The present invention relates to an image forming process with a stored program control and an apparatus therefor.
2. Description of the Prior Art
The present invention, though being explained in the following with reference to an electrophotographic apparatus, is also applicable to a printer for data print-out. In general an apparatus for automatic repeated formation of an electrophotographic image comprises a rotary photosensitive member around which there are provided, in the direction of rotation thereof, a means for forming an electrostatic latent image, a means for developing said latent image, a means for transferring the developed image onto a transfer sheet and a means for cleaning said photosensitive member for succeeding formation of electrostatic latent images thereon, wherein various devices for process steps have to be controlled with predetermined timings.
In the conventional process control the timings of functioning loads are determined by the signals from cam switches actuated by cams operated in connection with the angle of said rotary photosensitive member, or by counting a series of pulses generated by the rotation of said photosensitive member. In such case, if said cam signals or pulse signals are supplied to a so-called computer to control the sequential release of timing function signals, it becomes necessary to constantly inspect the generation of such cam signals or pulse signals, and it is difficult to achieve a process other than the sequence function. Particularly in the latter case, since the frequency of clock signals for data processing in the computer (for example 1 .mu.sec.sup.-1) is much higher than that of the above-mentioned pulse signals, it becomes necessary to realize certain timing processes between the computer operations and pulse counting, thus requiring additional programs and memories. Further, in case of a sequential process control of a copying process with a computer, the programmed control allows for detection of an emergency such as paper jamming only at predetermined timings, giving rise to the belated application of safety measures.